A thin film transistor liquid crystal display (TFT-LCD) has the advantages of small size, low power consumption and no radiation. The TFT-LCD has been developed rapidly in recent years, and dominates the current market of panel display. The TFT-LCD is widely used in products with various kinds of size, which covers main electronic products in current information society, such as LCD TV, high definition digital television, computer, mobile phone, car display, projection display, camcorder, digital camera, electronic watch, calculator, electronic equipment, instrument, public display and unreal display, etc.
The TFT-LCD consists of a liquid crystal display panel, a driving circuit and a backlight module, and the liquid crystal display panel is an important component of the TFT-LCD. The liquid crystal display panel is formed by injecting liquid crystal between an array substrate and a color filter substrate, then edges of which are sealed by using seal agent, and then providing polarizers having polarization directions perpendicular to each other on the array substrate and the color filter substrate, respectively. Thin film transistors, pixel electrodes and peripheral circuits are arranged in a matrix-type manner on the array substrate. In the color filter (CF) substrate, a pixel consists of resins of three primary colors of red (R), green (G) and blue (B), and a transparent common electrode is formed.
Referring to FIGS. 1 and 2, the liquid crystal display panel includes a TFT array substrate, a color filter substrate and a liquid crystal layer provided between the TFT array substrate and the color filter array substrate (not illustrated). The TFT array substrate includes a gate 11, a gate line 12 provided at the same layer as the gate 11 and made of the same material as the gate 11, a transparent conductive common electrode 20, a first insulation layer 30, an active layer 40, a data line layer 50 comprising a data line 501, a source 502 and a drain 503, and a pixel electrode 60. The gate 11, the first insulation layer 30, the active layer 40 and the data line layer 50 form a thin film transistor, the gate line 12 is used for supplying turning-on signal to the thin film transistor, and the data line 501 is used for supplying data signal to the pixel electrode 60. The pixel electrode 60 is also a transparent conductive layer and provided at the same layer as the data line layer 50, and the pixel electrode 60 is electrically connected to the drain 503. In order to allow the electrical field between the common electrode 20 and the pixel electrode 60 to affect the liquid crystal provided between the array substrate and the color filter substrate, the pixel electrode 60 is generally designed as a plane-hollowed structure, as shown in FIG. 3. In addition, the pixel electrode 60 may be formed after the data line layer 50 is formed by a patterning process; alternatively, the data line layer 50 may be formed after the pixel electrode 60 is formed by pattering process. Here, the pattering process mainly includes procedures of film coating, exposing, etching, etc.
The array substrate further includes a passivation layer 70 provided on the thin film transistor, the passivation layer 70 protects the thin film transistor from corrosion. The display panel further includes a black matrix 80 provided above the color filter substrate, the black matrix 80 is used for shielding a light leakage region. An region defined by a dashed line AA′ and a dashed line BB′ is a thin film transistor region or is referred to as a non-display region of the pixel unit (simply referred to as non-display region), and a region defined by a dashed line CC′ and the dashed line BB′ is a display region of the pixel unit (simply referred to as display region).
In prior art, the procedure of fabricating the above mentioned array substrate includes:
Step 1, depositing a non-transparent metal film layer on a base substrate 10, and forming a pattern comprising the gate 11 and the gate line 12 by a patterning process;
Step 2, depositing a transparent conductive film layer on the pattern comprising the gate 11 and the gate line 12 by a magnetron sputtering method, and forming the transparent common electrode 20 by a patterning process;
Step 3, depositing a silicon oxide or silicon nitride layer on the pattern comprising the common electrode 20 to form the first insulation layer 30;
Step 4, forming an amorphous silicon film layer on the first insulation layer 30, and forming a pattern comprising the low temperature poly-silicon active layer 40 by a patterning process;
Step 5, forming a source and drain metal film on the pattern comprising the active layer 40, and forming a pattern comprising the data line 501, the source 502 and the drain 503 by a pattering process;
Step 6, depositing a silicon nitride or silicon oxide layer on the pattern comprising the data line 501, the source 502 and the drain 503, to form the passivation layer 70 for protecting the thin film transistor from corrosion, and forming a via hole in the passivation layer 70 by a patterning process; and
Step 7, depositing a transparent conductive film layer of indium tin oxide on the passivation layer 70 by a magnetron sputtering method, and forming a pattern comprising the pixel electrode 60 by a patterning process, the pixel electrode 60 being connected to the drain 503 through the via hole.
As can be seen from the above discussion of the method of fabricating the thin film transistor array substrate in prior art, the method requires at least seven patterning processes such as exposing, etching, etc., and there exists problems of complicated fabricating process, numerous fabricating procedure, high cost and long time consuming in the method.
Further, in order to block the light from the light leakage region, in the display panel in prior art, the black matrixes are provided on the color filter substrate. In the design, a width of the black matrix is equivalent to a sum of a width of the light leakage region and a tolerant error or permissible error for alignment of the array substrate and the color filter substrate (hereinafter referred to as the alignment permissible error). Since the alignment permissible error is relatively great, the width d1 of the black matrix provided on the color filter substrate is relatively great, resulting in defects of low aperture ratio and low display luminance in the TFT-LCD.